[Blood morphology of the European eel (Anguilla anguilla). IV. Thrombocytes and their developmental stages].

By the aid of histological special stainings, cytochemical proofs, phase contrast and electron microscopical methods the thrombocytes (spindle cells) of the European ell (Anguilla anguilla) and their stages of development were described as an independent series of cells. After an artificial blood loss thrombocytoblasts, prothrombocytes and mature thrombocytes could distinctly be demonstrates. Besides the kidney the spleen was found to be the main place of the thrombopoiesis. Phase contrast investigations provided evidence for the relatively strong locomotion of these cells. By means of cytochemical proofs a further differentiation of the thrombocytes from other white blood cells can be made. Electron microscopical investigations of the thrombocytes yielded a great similarity to the thrombocytes of the amphibians. The endoplasmatic ring and particular inclusions could be shown to be characteritstic features of the fine structure.